To assure that the MIT Mass Spectrometry Facility remains in the forefront of the field, core research will be carried out to (1) increase the sensitivity of high performance tandem mass spectrometry by using an improved array detector and thus decrease the sample requirements; (2) expand the applicability of tandem mass spectrometry to molecular ions larger than the present limit (about 2500-3000 daltons) by their photodissociation with a laser beam; (3) develop and improve data acquisition and processing capabilities; and (4) acquire a new laser ionization time-of-flight mass spectrometer to measure molecular weights in the range of 1,000 - 200,000 daltons with an accuracy of + 0.1%. These methods will be developed with and applied to peptides, proteins, glyco-and lipoproteins, carbohydrates, glycoconjugates, and related compounds. This new as well as the existing methodology will be made available to the biomedical community through collaboration or as a service.